PATTERN OF SHIFT ROTA MODULATES ORAL-TEMPERATURE CIRCADIAN-RHYTHM ANDSLEEP-WAKEFULNESS PROFILES IN SHIFT WORKERS

Twenty four shift workers (8 from a steel industry and 16 from a Gover nment hospital) participated in the study. The subjects were instructe d to self-measure oral temperature, 4-6 times a day for about three we eks. Sleep quantity and quality for each subject were analysed with th e help of an appropriate inventory. The data were analysed by cosinor and power spectrum methods. The frequency of circadian rhythm detectio n was in the order of 48% in senior nurses, 29% in steel plant workers and 14% in junior nurses. These were also complemented by the results of power spectrum analysis. Present results suggest that rhythms of s ubjective fatigue and subjective drowsiness are governed neither by or al temperature oscillator nor by the sleep/wake cycle oscillator. The results show that shift rotation pattern chiefly modulates the circadi an time structure of shift workers. It is also suggested that the phen omenon of circadian rhythm desynchronization in oral temperature appea rs to be independent of per day total sleep length.